IMPROVED ROOF ANCHOR

Abstract: An improved roof anchor (10) is described which includes U-bolt (24) the upper end of which extends above a slate-piece (22) to provide an attachment point for a safety harness. The legs (26, 28) of the U-bolt (24) pass through the slate-piece and sarking and extend down the sides of truss (12). The lower ends of the legs are threaded and extend through apertures on lower plate (32) to receive nuts and washers (34) to clamp plate (32) against the truss (12). An upper plate member (36, 52) is located on the upper surface of the surface of the sarking and below the slate-piece (22). Convex washers (40, 42) are attached to the upper surface of the plate member (36, 52) for engaging the underside of the slate-piece (22) and complementary washers (44, 46) are welded on legs (26, 28) whereby portions of the slate-piece around the apertures (45) are clamped between washer pairs (40, 44) and (42, 46). In the event of a fall, a force applied to the U-bolt via a harness is resisted by upper plate member (36, 52) acting on the upper face of the truss (12) and the lower plate (32) acting on the lower face of the truss (12) distributing the force along the truss so as to minimise bending movements. The attachment point can incorporate a ladder hook. Embodiments of the invention are described.

Description: IMPROVED ROOF ANCHOR This invention relates to an improved roof anchor and in particular, but not exclusively, to an anchoring device for use on sloping roofs and to which a lanyard with a safety harness or anchorage line with safety harness or other similar device may be secured, or from which a roof ladder may be suspended. There have been various proposals for roof anchoring devices which are secured to various elements of a roof such as a truss or the ridge so that an anchoring element, usually an eyebolt, projects through the roof surface and to which a safety harness or the like may be secured. Examples of such devices are disclosed in GB A 2071196, GB A 2219826 and GB A 2251020. For location on a traditional sloping tiled roof, the roof anchor will typically have a portion which extends through a lead slate-piece, such as described and illustrated in GB A 2251020. It is important that the seal between the roof anchor and slate-piece is watertight and also that the formation of the seal does not damage the slate-piece. The arrangement disclosed in GB A 2251020 provides a seal by providing an arrangement of concave washers on either side of the slate-piece around the aperture in the slate-piece through which the eyebolt extends. However, the roof anchor assembly disclosed in GB A 2251020 comprises a relatively large number of parts requiring machining or forming. The anchorage clamp disclosed in GB A 2071196 is of simpler construction and is adapted for location on the ridge of a roof. However, the clamp does not include any provisions for forming a seal with a slate-piece or other roof covering, to prevent the ingress of moisture around the clamp. Other forms of anchors are disclosed in US A 4 932 185, EP A 0 141 730 and GB A 1 541 016. It is among the objects of the present invention to provide a secure roof anchor which comprises relatively few parts, is relatively simple to manufacture and fit, and which also provides for an effective seal between the exterior and interior of the roof covering. It is a further object of the invention to provide a roof anchor which will comply with the appropriate local Standards without requiring unduly heavy construction. According to the present invention there is provided a roof anchor for use on a roof having a plurality of trusses with an external roof covering including a deformable member thereon, the roof anchor comprising: a roof penetrating member having an attachment point and legs coupled to the attachment point for passing through the deformable member and passing down the sides of a truss, each leg of the roof penetrating member including a first surface for engaging an outer side of the deformable member around an aperture formed therein to accommodate the leg; an upper member for location beneath the deformable member and for transferring force applied to the attachment point of the roof penetrating member to an upper face of the truss, the upper member defining apertures to receive the legs of the roof penetrating member and providing mounting for respective second surfaces for engaging the inner side of the deformable member, the roof penetrating member and the upper member being adapted to provide a seal between the first and second surfaces around the apertures formed in the deformable member; and a lower member for engaging a lower face of the truss and adapted for engaging and retaining the lower ends of the legs of the roof penetrating member. Preferably, the roof penetrating member is generally U-shaped. The attachment point provided by the member may be suitable for securing a lanyard with a safety harness or anchorage line with safety harness, or may be in the form of a ladder hook. The attachment point may be formed of an eyelet disposed 90° to the legs of the U. Preferably also, the upper member is in the form of a plate. The lower member may also be in the form of a plate. Preferably also, the first and second surfaces are arranged so that the first and second surfaces engage the respective outer and inner sides of the deformable member so as to raise part of the deformable member near to the centre of said respective first and second surfaces above the part of the deformable member at the periphery of said first and second surfaces. Preferably also, the spacing between the second surfaces defined by the upper member and a lower face of the upper member for engaging an upper face of the truss or the upper surface of the roof sarking, where provided, is such that the portion of the deformable member extending beyond the second surfaces may be substantially planar. This permits the roof anchor to be fitted without creating a depression, where water will lie, in the deformable member. The upper member may be formed of a single part, or may be formed of a number of separable parts. Conveniently, the upper member may comprise a spacer member for engaging the truss or sarking and a plate which carries the second surfaces. Most conveniently, the spacer member is formed of a block of preservative treated wood and the plate is formed of steel. If formed of a single part, the upper member conveniently comprises a metal plate for engaging the truss or sarking, the second surfaces being provided on the upper ends of bosses welded to the plate. The bosses should be of sufficient strength or suitably supported or reinforced to withstand forces of the magnitude which would be applied to the attachment point at the upper end of the roof penetrating member and thus to the bosses in the event of an operator attached to the anchor falling from the roof without significant deformation to the roof penetrating member or the bosses. Preferably also, the lower ends of the legs of the roof penetrating member are threaded so that nuts may be used to secure the lower member thereto and clamp the anchor to the truss. Preferably also, the first surfaces may be provided by washers or the like of suitable configuration mounted to the legs of the roof penetrating member. Also, the second surfaces may be provided by washers secured to the upper surface of the upper member. This aspect of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a roof anchor in accordance with a first embodiment of the present invention, shown mounted on a roof truss; Figure 2 is a side view of the roof anchor of Figure 1, and showing further roof elements; Figure 3 is a view in the direction of arrow 3 of Figure 2, showing roof elements in section; Figure 4 is a perspective view of a roof anchor in accordance with a second embodiment of the present invention, shown mounted on a roof truss; Figure 5 is a side view of the roof anchor of Figure 4, and showing further roof elements; Figure 6 is a view in the direction of arrow 6 of Figure 5, showing roof elements in section; Figure 7 is a perspective view of a roof anchor in accordance with a third embodiment of the present invention, shown on a roof truss, and Figure 8 is a perspective view of a roof anchor in accordance with a fourth embodiment of the invention. Reference is first made to Figures 1, 2 and 3 of the drawings which illustrate a roof anchor 10 in accordance with a first embodiment of the present invention clamped to a roof truss 12. As may be seen more clearly in Figure 2, the anchor 10 is shown on a sloping portion of roof. The roof is of conventional construction with sarking 14 provided over the roof trusses 12 and counter battens and tile battens 16, 18 being provided to mount tiles 20 on the roof. At the roof anchor location a tile has been removed and replaced with a lead slate-piece 22. The roof anchor 10 includes a stainless steel U-bolt 24, the upper end of which extends above the slate-piece 22 to provide an attachment point for a lanyard or safety harness. The legs of the U-bolt 26, 28 extend through the slate-piece and sarking 22, 14 and down the sides of the truss 12. The lower ends of the legs 26, 28 are threaded and extend through apertures provided in a lower plate 32. Nuts and washers 34 are provided on the threaded ends of the legs 26, 28 to clamp the plate 32 against a lower surface of the truss 12. Located on the upper surface of the sarking 14 and below the slate-piece 22 is an upper plate member in the form of a timber packing piece 36 and a metal plate 38. The packing piece and plate are nailed to the sarking and truss 14,12, the nail-heads 39 being seen in Figure 1. Both the packing piece and plate 36, 38 are apertured to accommodate the legs 26,28. Welded to the upper surface of the plate 36 are two convex surfaced washers 40,42 which engage the lower surface of the slate-piece 22. Complementary washers 44,46 are welded on the legs 26,28, the arrangement being such that the portions of the slate-piece around the apertures 45 (only one shown in Figure 2) which accommodate the legs 26,28 are clamped between the respective washers 40,44 and 42,46. The complementary convex and concave forms of each pair of washers raise the portion of the slate-piece 22 near to the respective aperture 45 above the part of the slate-piece at the periphery of the washers, and this arrangement assists in preventing the ingress of moisture through the apertures 45. Also, the spacing of the washers 40,42 from the surface of the sarking 14 is controlled by the thickness of the packing piece and plate 36,38, such that the slate-piece 22 is substantially planar and thus fitting of the anchor does not create a water collecting depression around the apertures 45. Clearly, the thickness of the packing piece 36 may be varied to suit particular applications. The relative dimensions of the U-bolt 24, plates 32, 38 and the packing piece 36 are selected according to the material used and to withstand forces of the magnitude which would be applied to the upper end of the U-bolt 24 in the event of an operator attached to the anchor falling from the roof without significant deformation. In the event of such a fall, the force applied to the upper end of the U-bolt 24 will be resisted by the upper plate 38 acting on the packing piece 36, which in turn acts on the sarking 14 and the upper face of the truss 12, and the lower plate 32 acting on the lower face of the truss 12. The location of the upper plate 38, spaced from the sarking and truss 14, 12, also minimises the length of U-bolt which is unsupported and thus reduces the bending moments, and subsequent possibility of deformation, to which the U-bolt is subject. Conveniently the U-bolt 24, and washers 44, 46 are formed of stainless steel. The upper plate 38 and washer 40, 42 are conveniently of galvanised steel, and the packing piece 36 is formed of pressure or vacuum treated timber. As the lower plate 32 will not be exposed to the same degree of weathering as the other parts of the anchor it may be formed of a less corrosion resistant steel. The above described roof anchor 10 may be fabricated from a minimal number of parts in a very short time, the only significant machining step involved being the formation of the threads on the U-bolt 24. Also, fitting the roof anchor 10 is a very straightforward procedure, and the fitted anchor presents a very low profile and thus is not visually intrusive. Further, such a roof anchor 10 may be constructed to conform with appropriate local standards, such as the British and European Standards, without requiring the use of unduly heavy sections or components. Reference is now made to Figures 4, 5 and 6 of the drawings which illustrate a roof anchor 50 in accordance with a second embodiment of the present invention. Many of the features of the roof anchor 50 are similar to the features of the roof anchor 10 described above with reference to Figures 1, 2 and 3 and the same reference numerals are used to indicate these similar features. The difference between the two embodiments lies in the upper plate member 52 which, in this roof anchor 50, is in the form of a single, fabricated metal part. The plate 52 comprises a base plate 54 which lies on the sarking 14. Welded to the plate 54 are two bosses 56, 58 which provide mounting for the washers 40, 42. Also welded to the plate 54 is a stiffening spine 60 which increases the modulus of the plate 54. A flange 62 is welded to the upper surface of the spine 60 and also to the bosses 56, 58 to assist the bosses in resisting the bending moments which would be applied to the bosses in the event of forces being applied to the attachment point by an operator falling while secured to the anchor 50. Reference is now made to Figure 7 of the drawings, which illustrates a roof anchor in accordance with a third embodiment of the present invention. The anchor is very similar to the first described embodiment, and the same reference numerals are used for similar parts. However, it will be noted that the U-bolt 124 is considerably longer and is bent above the slate-piece 22 to form a hook 126, suitable for mounting a ladder on the roof. Also, the U-bolt 125 has a cross-bar 128 extending between the legs of the bolt, to provide a harness anchor. In the event of a fall, the cross-bar 128 spreads the load to both legs of the U-bolt 124, rather then having the shock load concentrated on one leg. If the anchor is to be used solely as a ladder hook, the cross-bar 128 may be omitted. Reference is now made to Fig. 8 of the drawings which depicts a roof anchor in accordance with a fourth embodiment of the present invention and in which like numerals refer to like parts but with the prefer '2' . This is substantially identical to that shown in Fig. 1 except that the upper end of the stainless steel U-bolt 224 is sufficiently long so that it can be twisted through 90° as shown to create an eye which has a narrower profile than the other embodiments. This means that only a single slate may be removed thus minimising the width of the cut-out in the roof covering such as a tile or slate. This narrow profile is also aesthetic in that it minimises distraction from the roof which is particularly advantageous for use in conservation areas. This anchor is readily manufactured by cutting a rod of predetermined length and threading the ends with 3 /4" (7.5-10cm) of threads. The threaded rod is then bent to form a U. The legs of the U are then fixed in a mandrel and a former of suitable diameter is inserted at the base of the U which is then twisted through 180°. It will be clear to those of skill in the art that the above described embodiments are merely exemplary of the present invention and that various modifications and improvements may be made to these embodiments without departing from the scope of the present invention.

Claims: CLAIMS 1. A roof anchor for use on a roof having a plurality of trusses with an external roof covering including a deformable member thereon, the roof anchor comprising: a roof penetrating member having an attachment point and legs coupled to the attachment point for passing through the deformable member and passing down the sides of a truss, each leg of the roof penetrating member including a first surface for engaging an outer -side of the deformable member around an aperture formed therein to accommodate the leg; an upper member for location beneath the deformable member and for transferring force applied to the attachment point of the roof penetrating member to an upper face of the truss, the upper member defining apertures to receive the legs of the roof penetrating member and providing mounting for respective second surfaces for engaging the inner side of the deformable member, the roof penetrating member and the upper member being adapted to provide a seal between the first and second surfaces around the apertures formed in the deformable member; and a lower member for engaging a lower face of the truss and adapted for engaging and retaining the lower ends of the legs of the roof penetrating member. 2. A roof anchor as claimed in claim 1 wherein the roof penetrating member is generally U-shaped. 3. A roof anchor as claimed in claim 1 or claim 2 wherein the attachment point is suitable for securing a lanyard with a safety harness or anchorage line with safety harness. 4. A roof anchor as claimed in any preceding claim wherein the attachment point includes a ladder hook. 5. A roof anchor as claimed in any one of claims 1 to 3 wherein the attachment point is provided by an eyelet disposed at 90° to the legs of the U. 6. A roof anchor as claimed in any preceding claim wherein the upper member is in the form of a plate. 7. A roof anchor as claimed in any preceding claim wherein the lower member is also in the form of a plate. 8. A roof anchor as claimed in any preceding claim wherein the first and second surfaces are arranged so that the first and second surfaces engage the respective outer and inner sides of the deformable member as as to raise part of the deformable member near to the centre of said respective first and second surfaces above the part of the deformable member at the periphery of said first and second surfaces. 9. A roof anchor as claimed in any preceding claim wherein the spacing between the second surfaces defined by the upper member and a lower face of the upper member for engaging an upper face of the truss or the upper surface of the roof sarking, where provided, is such that the portion of the deformable member extending beyond the second surfaces may be substantially planar. 10. A roof anchor as claimed in any preceding claim wherein the upper member is formed of a single part. 11. A roof anchor as claimed in any preceding claim wherein the upper member comprises a spacer member for engaging the truss or sarking and a plate which carries the second surfaces. 12. A roof anchor as claimed in claim 11 wherein the spacer member is formed of a block of wood and the plate is formed of steel. 13. A roof anchor as claimed in any one of claims 10 to 12 wherein the upper member comprises a metal plate for engaging the trust or sarking, the second surfaces being provided on the upper ends of bosses welded to the plate. 14. A roof anchor as claimed in any preceding claim wherein the lower ends of the legs of the roof penetrating member are threaded so that nuts may be used to secure the lower member thereto and clamp the anchor to the truss. 15. A roof anchor as claimed in any preceding claim wherein the first surfaces are provided by washers or the like of suitable configuration mounted to the legs of the roof penetrating member. 16. A roof anchor as claimed in any preceding claim wherein the second surfaces are provided by washers secured to the upper surface of the upper member.

Inventors: CRAWFORD HENRY, CRAWFORD, HENRY
Applicants: CRAWFORD HENRY, PATERSON & SON, CRAWFORD, HENRY
Application year: 1994
Main classification: E04D13
IPC codes: E04D13, E04G21